Polycyclic hydrocarbon-responsive mice were injected every five days with beta-naphthoflavone to induce aryl hydrocarbon hydroxylase (Ah) activity and fed acetaminophe (or naphthalene-) impregnated food bars. Lenticular opacities as well inflammation of the ciliary body and iris, developed within a few weeks. Body weight was not affected. Ocular abnormalities were not observed in nonresponsive mice. The geneticallly well-characterized mouse strains should be useful for studies of ocular toxicity of drugs and environmental chemicals. Gamma-glutamyl transpeptidase (an enzyme involved in mercapturic acid formation) was purified from bovine ciliary body, kidney, liver, spleen, and brain. Enzymes showed different electrophoretic mobilities. After neuraminidase treatment, however, the enzymes migrated at essentially identical rates. Thus, tissue differences in the glycoprotein enzyme are attributed to the varying extent of sialylation.